The pattern papers of the parts which will become components of a Low temperature differential Stirling engine for DIY Beginners are provided by MS-Word file. To make the Stirling engine for DIY Beginners requires to read both the explanation on the pattern papers and another manual. All the explanations are written in Japanese.

After gaining a variety of experiences related to the Alternative ☆ Energy Contest and LOHAS engineering, I came up with the idea of challenging myself to use backcasting to show the direction (policies) that mechanical engineering should aim for, with regard to the idea that won the Technology and Society Department Excellent Exhibition Award (Alternative ☆ Energy Contest section). In this paper, I attempt to show the direction we should aim for using backcasting, based on the presentation poster for the idea "Light and Heat Combined Greenhouse," which was selected for the Excellent Exhibition Award at the 14th Alternative ☆ Energy Contest adopted as Interdisciplinary Initiative No. 12 in 2021. Some of the contents of this report have already been presented at Organized Session J201 of this conference in 2024.

The Alternative ☆ Energy Contest is a new contest on "energy utilization" mainly for university and technical college students, which started in 2008 as an event in which the technology and society departments of the JSME cooperate. The mark "☆" in the title of the contest indicates something that goes beyond the preconceived notions of alternative energy, and the essence of this contest that appeals for novel ideas appears there. From 2012, the year after the Fukushima nuclear accident caused by the Great East Japan Earthquake, a stationary event was held at the College of Engineering, Nihon University located in Koriyama City, Fukushima Prefecture, as an event to watch over the reconstruction of Fukushima. The 18th meeting (October 25th, 2025) is scheduled to be held on the onsite and website with the College of Engineering, Nihon University as the operating base. We are grateful for the opportunity to give an overview of this contest at this civic forum in this paper.

The Alternative ☆ Energy Contest was launched in 2008 as the new energy utilization contest for students of universities and National Institute of Technologies, which was held in collaboration with Technology and Society Division, The Japan Society of Mechanical Engineers. In this report, the number of applications, participants and sponsoring companies were investigated in the 17th Alternative ☆ Energy Contest held at College of Engineering, Nihon University on Saturday, October 19, 2024. In addition, we classified the energy sources and energy conversions in the presentation.

At first, the definition of Extended Digital Twins will be explained. Then the capability of Generative AI to recognize and generate Human Uncertainty including Emotions and Creativity will be explained. Especially, diversity of individual Emotions will be investigated. Then, integrating Generative AI and Knowledge Graphs will be introduced in order to convert and structure tacit Knowledge into explicit Knowledge. Finally, the relationship between Extended Digital Twins and Human Augmentation will be discussed.

This study proposes a new framework for creating semantic value in products and services by integrating a scientific understanding of human recognition and emotion into the design process. A case study on product sound quality design demonstrates that existing artifacts can be reinterpreted through new contexts, enabling the generation of innovative meanings—a process referred to as “innovation of meanings.” Human recognition is mathematically modeled using Bayesian brain theory, which reveals that recognized meanings are influenced by both observations and contextual factors. Furthermore, emotional mechanics are formulated within a Bayesian framework, allowing the quantitative evaluation of receptivity to new meanings through information gain and optimal levels of surprise. These elements are shown to play a crucial role in eliciting positive emotional responses. Looking ahead, this work aims to apply these findings to develop design methodologies that promote curiosity, exploration, and acceptance of new ideas. Ultimately, the goal is to establish a design thinking approach that supports the creation of products and services with enriched semantic and affective value.

This paper examines value co-creation and social system design from a service engineering perspective. It introduces two modes of service engineering: Service Engineering 1.0 focusing on provider-side support and Service Engineering 2.0 emphasizing customer-side support and co-creation. The paper presents a value co-creation framework developed through the "Architecture for Next-Generation Manufacturing" program at the University of Tokyo, extending the traditional company-customer relationship to a triadic relationship among companies, employees, and customers. The framework features two complementary cycles: a traditional positive cycle linking employee engagement to customer satisfaction and enterprise value, and a new reverse positive cycle strengthening human, organizational, and customer capital through trust-building. Additionally, it introduces social system design methodology for analyzing negative cycles and designing positive cycles in organizational activities, along with "SSD Mentor," an LLM-based tool supporting this methodology. The integration of digital technology with human capital creates sustainable value creation systems in manufacturing, addressing challenges in knowledge transfer and employee engagement in global operations.

Monitoring the concentration of biological components is essential for assessing physiological conditions. Although blood sampling remains the most reliable method, its high invasiveness limits its suitability for continuous monitoring. To enable minimally invasive and continuous measurement of biological components, we have developed thin, needle-shaped devices capable of detecting concentration changes within the skin. Acupuncture needles were selected as the base material due to their excellent skin penetrability and mechanical rigidity. Using a custom-developed non-planar microfabrication technique, functional microstructures were fabricated directly onto the needle surfaces. We developed two types of needle-based sensors, each based on a distinct measurement principle. The first employs a microperfusion-based approach, wherein a microfluidic channel with a perforated membrane is integrated onto the needle. A perfusate is circulated through the channel to extract biological components from the interstitial fluid, enabling continuous sensing by analyzing the collected fluid outside the body. The second device utilizes an integrated micro-optical waveguide to deliver near-infrared light into the skin, where absorbance is measured to estimate the concentration of specific biological components. These devices have demonstrated the capability to estimate concentrations of target analytes such as lactate and glucose without the need for conventional blood sampling, offering a promising platform for minimally invasive and continuous health monitoring.

The adrenal glands, crucial endocrine organs located above the kidneys, produce steroids essential for maintaining body homeostasis. Steroid production must be tightly regulated by the hypothalamic-pituitary-adrenal axis, which responds to stress levels through feedback mechanisms involving CRH, ACTH, and cortisol, thereby adjusting to changing stress levels. Patients with adrenal insufficiency require lifelong steroid replacement therapy. The difficulty in controlling physiological steroid levels results in possible life-threatening side effects. Novel treatments for adrenal insufficiency are thus sought. We established human iPSC-derived adrenal organoids that maintain a physiological adrenal zonal structure, comprising capsular-like cells, definitive zone-like cells, transitional zone-like cells, and fetal zone-like cells, as well as ACTH-dependent steroid production, demonstrating promise for responsive steroid production in response to stress levels. Additionally, the organoids contain an adrenal stem cell population, which ensures long-term therapeutic effects. These features of the adrenal organoids show the potential applications in regenerative therapies for adrenal insufficiency. Current efforts focus on developing treatment models using adrenal organoids for adrenal insufficiency in immunodeficient mice.

The authors have developed a cancellous bone-inspired stochastic network (CBSN), which has isotropic interconnection and orientation of the struts with stochastically determined beam lengths and bifurcation counts, without any repeated units. This study reported the effect of material, build direction of powder bed fusion using a laser-beam (PBF-LB), and compressive loading direction on mechanical properties in CBSN. A cubic model with volume fraction about 40% was generated. The diameter and mean length of struts and the mean bifurcation count in the model were analyzed. The model was manufactured with PBF-LB/stainless steel 316L and maraging steel. To investigate build direction and compressive loading direction on mechanical properties in CBSN, SUS316L specimens were manufactured in each three principal axes of the model respectively. The compressive tests were conducted in same or different direction of building. In SUS316L and MAS parts, it was found that the effect of the structure became more dominant than the material properties in the behavior after the initial yield. In SUS316L parts, the elastic modulus, offset stress, plateau stress, and energy absorption showed isotropic without dependence of build directions, which suggests that CBSN may reduce the effects of anisotropy by the PBF-LB building direction.

Although mechanical element technology such as gears and screws is essential for power transmission and element fastening, it is generally considered to be a mature technology, and mechanical engineering students have little interest in it. In this paper, we introduce the mechanical element technology education at Doshisha University's Department of Mechanical Engineering as an example of a private university.

This report introduces the educational content related to machine elements studies at the Tokyo Metropolitan College of Industrial Technology. The days when engineering was represented by mechanical, electrical and chemical fields are long gone, and nowadays, in addition to the fields of electronics and control, the information field has become more important. At our schools, which mainly offer combined courses in which students study a wide range of fields, the number of fields to be covered is increasing year by year. However, the five-year study period remains the same, so if the number of fields to be covered is increased, the existing fields have to be reduced. Thus, the time available for studying machine elements is decreasing. Therefore, it is important for teachers to be able to introduce students to as much of the contents of machine elements studies as possible in a small amount of time. In this presentation, some of the ideas which teachers are using are introduced.

I teach lectures related to mechanical elements at the university. I am always thinking about having a place to exchange opinions on the current state and future state of mechanical element education in higher educational institutions. The content I teach is based on the content of the lectures I received as a student. The time available for mechanical element education at universities is decreasing year by year, and the topics that can be conveyed to students are inevitably limited. On the other hand, companies that accept graduates must have educational content that they require from higher educational institutions such as universities. We are always aware of the need to respond to the demands of companies. Therefore, five people from universities, technical colleges, and companies will provide topics from their respective positions and exchange opinions. I will provide a topic on the current state of education at Yamagata University from the perspective of mechanical element education at a local national university. I will mainly introduce the content of the lecture on design engineering.

Due to their safe interaction and dexterous movements, continuum robots have potential applications in logistics, agriculture, and domestic assistance. However, they often struggle with their limited reach and unstable deformation behavior. To address this, we introduce REACH (Robotic Extensible Arm inspired by Carpenter bird’s Hyoid), a novel continuum robot. It features a unique extension mechanism inspired by the woodpecker's tongue, achieving both long reach and stable deformation.

Prime structures are the structures which do not include 0-DoF subchains, and they are expected to be used in the systematic kinematic analysis and design of link mechanisms. This paper explains the number synthesis and the configuration analysis of spatial prime structures, as well as the analysis and design of spatial mechanisms based on spatial prime structures. First, the exhaustive enumeration (number synthesis) of spatial prime structures is described. The numbers of kinematic pairs are calculated, and then the candidates of prime structures are exhaustively enumerated. By eliminating inappropriate candidates, spatial prime structures are enumerated without omissions or duplications. Next, the configuration analysis of spatial prime structures is described. For some single-loop prime structures, the configuration can be analyzed by considering the intersection of multiple spatial figures. Finally, the analysis and design of spatial mechanisms based on spatial prime structures are described. When the driving link of a mechanism is fixed, the remaining chain becomes a structure. By analyzing the configuration of the structure using prime structures, the kinematics of the spatial mechanism can be analyzed. Furthermore, when the systematic kinematic analysis of spatial mechanisms becomes possible, it can be applied to the mechanism design.

The Model Based Development (MBD) is the adoption of digital technology to transform real machinery to virtual machinery. MBD of Autonomous Transportation and Logistics machinery is investigated.

This paper presents a framework for symmetry-guided multi-domain modeling based on the preservation of canonical structure. Using the co-Hamiltonian formalism with velocity and force as state variables, we derive motion equations that remain invariant under canonical transformations. We show that such transformations enable consistent mappings between physical variables across different domains—such as mechanical and fluidic systems—while preserving energy-conserving and causal structures. Furthermore, we demonstrate that generating functions systematically define these transformations, and that physical function models serve as graphical representations of the co-Hamiltonian dynamics and canonical transformations. This approach provides a theoretical foundation for structure-preserving, multi-domain modeling rooted in analytical mechanics.

This report proposes a model that precisely estimates the state variable of NOx storage reduction (NSR) catalysts (i.e., the NOx storage amount) for the purpose of improving fuel consumption by optimizing the control of an NSR catalyst. The proposed model combines neural networks (NNs) and a physical model, and it is based on the mass conservation law in order to estimate NOx storage amount. Compared with a model that does not consider mass conservation (i.e., a model composed only of an NN), the proposed model decreases both the maximum and mean absolute error of the NOx storage amount by at least 80%. This result confirms the effectiveness of the proposed model. To implement the proposed model in an in-vehicle ECU, it is necessary to use only variables that can be acquired on the vehicle as the input variables of the proposed model. The catalyst bed temperature, which is one of the input variables for the model, is difficult to measure on the vehicle. In this report, UKF (Unscented Kalman Filter) is designed for the purpose of estimating the catalysts bed temperature averaged in the flow direction. By inputting the catalyst bed temperature estimated using UKF into the proposed model, it was possible to estimate the NOx storage amount with good accuracy. The maximum absolute error was 30.46 mg (2.2% of the correct value) in all sections.

In this paper, we propose the concept of a microrobot that resembles a cell, fabricated by integrating functional biomaterials that occur naturally within cells, most notably DNA and proteins. This strategy offers a promising avenue for constructing robotic devices on the micrometer scale. Furthermore, we present the distinctive molecular systems and cell-like microrobots we have engineered, which display unique functions that arise from the rational combination of components derived from DNA and proteins.

Intestinal cells are continuously exposed to various mechanical stimuli, such as shear stress generated by blood flow and contractile stress caused by peristalsis. These dynamic environmental forces play essential roles in regulating intestinal function and maintaining homeostasis. However, replicating these mechanical stimuli, such as fluidic flow and contractile stress, remains challenging when using conventional intestinal models like colon cancer cell lines or intestinal organoids. To overcome this limitation, a microphysiological system (MPS) has been developed. MPS is a cell culture platform that utilizes microfluidic devices to simulate physiological conditions, including mechanical stimuli induced by blood flow and peristaltic motion. Intestinal MPS makes it possible to investigate how mechanical forces contribute to intestinal homeostasis and influence the pathophysiology of intestinal diseases. Indeed, recent studies have successfully recapitulated the pathophysiology of intestinal infectious diseases and inflammatory enteritis using intestinal MPS, revealing the detailed mechanisms of tissue injury and host–pathogen interaction. Here, we introduce several existing intestinal MPS models and highlight their applications in intestinal disease research.

With a storage containing wet radioactive waste such as fuel debris, it is important to reduce the risk of explosion and combustion due to hydrogen generated by radiolysis of water. This study, as a part of the development of simulation technologies for verification of reduction countermeasures and proposal of new countermeasures, conducted a trial simulation of the hydrogen concentration behavior in a room installed the hydrogen recombination catalyst. The simulation using a CFD code focuses on reduction effect of hydrogen concentration by combination to catalyst and vent. It was found that the hydrogen concentration distribution was affected by formation of circulating flows in a room by flow resistance of catalyst and vent.

Hydrogen fuel cell railway vehicles are being developed as part of global efforts to decarbonize the railway sector. For their practical implementation, safety assessments are essential, particularly concerning hydrogen leakage in enclosed environments such as tunnels. The concentration of leaked hydrogen is strongly influenced by airflow conditions within the tunnel. This study employs numerical simulations to analyze hydrogen dispersion from a stationary two-car train situated inside a 400-meter-long single-track mountain tunnel on a conventional railway line in Japan. The leakage is assumed to originate from equipment mounted on the train roof. Simulations were conducted using the Fire Dynamics Simulator (FDS) developed by NIST. Results indicate that, in the absence of airflow, hydrogen concentration peaks directly above the leak source and rapidly decreases toward both tunnel portals, reaching the height of the overhead trolley wire. Conversely, even minimal airflow (less than 0.5 m/s) significantly reduces hydrogen concentration throughout the tunnel.

Efforts to expand hydrogen use to prevent global warming are underway, and its safe use is essential. Previously, it is demonstrated that a hydrogen leak and dispersion experiment using a hallway model (a garage) could be accurately reproduced using numerical simulations with the Fire Dynamics Simulator (FDS). Because obstacles in real structures increase hydrogen concentration and the risk of fire accidents, it is conducted numerical simulations to investigate the hydrogen concentration distribution when a hanging partition wall or other obstacles are installed. In this report shows results of simulations using different LES turbulence models and compared their effects on the hydrogen concentration distribution around a hanging partition wall. Differences in the hydrogen concentration distribution near the ceiling and hanging partition wall were observed depending on the turbulence model, suggesting that selecting an appropriate turbulence model is important for predicting the risk of ignition. In addition to the turbulence model, optimization of the grid spacing and wall boundary conditions is also considered important. Furthermore, to safely use hydrogen, it is necessary to develop methods for quickly detecting leaked hydrogen, predicting its spread and concentration even in the presence of obstacles, and preventing hydrogen accumulation.

To extract hydrogen from ammonia, which is a hydrogen carrier, it is necessary to separate hydrogen and nitrogen and then extract pure hydrogen gas so that the separation membrane has to be developed. Since Ti has excellent hydrogen solubility, Ti/Polyimide (PI) laminated membrane would be developed to further improve the hydrogen permeability and separation factor for hydrogen and nitrogen gases. The hydrogen/nitrogen permeability characteristics were evaluated using a gas permeability measurement system as the same as in our previous study and calculated the separation factor. The results showed that the Ti/PI laminate membrane exhibited a higher hydrogen permeability and that is a positive effect of Ti laminated but less separation characteristics than only PI membrane. On the other hand, the Ni/PI membrane, experimented in our previous study, exhibited a lower hydrogen permeability and higher separation properties than the PI membrane. From the results, it was found that the temperature dependence of the laminated membranes depends on the solubility of the laminated metal on the surface of PI membrane rather than the permeability.

Metal hydride is promising as safe hydrogen storage. However, the effective thermal conductivity of metal hydride is greatly affected by changes in the porosity of the packed bed. Therefore, this study was conducted to calculate the thermal properties of a metal hydride (LaNi₅) by using an inverse problem solution based on temperature measurements from heating experiments. Experiments were conducted at different metal temperatures (25 ℃, 30 ℃, 35 ℃) in order to confirm the differences in the experimental results at different metal temperatures. The porosity in this study is the average porosity of the entire packed bed, which was calculated from the observed images of the packed bed. As a result, the changes in porosity during the most recent cycle ranged from 50 % to 57 %, indicating that the packed bed is relatively stable. The temperature change data from the heating experiments at each porosity (reacted fraction) and at each metal temperature confirm that the thermal properties are different. However, the present process has not been able to find a trend of thermal property changes with differences in porosity (reacted fraction) and metal temperature. Therefore, we plan to reconsider the data processing method to calculate accurate thermal properties in the future.

Ultrasound-triggered disruption of microbubbles in drug delivery systems (DDS) is a promising technique for reducing side effects. Despite its potential efficacy in reducing side effects, the disruption ratio of the microbubble population remains poorly understood. In this study, we experimentally investigated the effects of diameter distribution and particle number concentration (PNC) of the microbubbles on their disruption ratio by quantifying the number of disrupted bubbles after ultrasonic irradiation. The experiments were conducted using polymer-shelled microbubbles suspended in a gelatin-filled microchamber and exposed to focused ultrasound at 1 MHz with 30 cycles. The size of microbubbles was sorted by filtration, and the concentration within the microchamber was determined by image processing. The disruption ratio of each microbubble population was evaluated as a function of PNC. The sorted microbubble population with resonant size exhibited a significantly greater disruption ratio, exceeding that of polydisperse populations by more than twofold. Moreover, the results showed an exponential decrease in the disruption ratio with increasing PNC, accompanied by a monotonic increase in the number of intact microbubbles. This suggests an increased risk of side effects even in the resonant-sized microbubble population at high PNC. Conversely, in the low PNC region, where the disruption ratio is higher, the lower number of disrupted microbubbles may lead to prolonging the treatment time. These findings highlight the necessity of determining an appropriate PNC by considering both treatment time and the risk of side effects.

Contrast-enhanced ultrasound imaging (CEUS) is a commonly used non-invasive technique for cancer detection that utilizes ultrasound contrast agents (UCAs). . However, its low signal-to-noise ratio (SNR) limits detectability in deep tissues and small vessels. To enhance acoustic scattering of UCAs, we have proposed the use of phase-inverted ultrasound excitation and assessed its effectiveness through both experimental and numerical evaluations. The phase-inverted field was generated by dividing the array elements into multiple groups and driving adjacent groups with opposite phases. Scattering coefficients under two-division and three-division driving methods were compared with conventional non-division driving one. In this study, 20 ± 9 μm microbubbles were insonified with a three-cycle burst wave at 1.38 MHz, and scattering was measured as a function of inter-bubble distance (IBD). The results showed that scattering increased as IBD decreased. Among the driving methods, three-division driving method yielded the highest scattering coefficient, exceeding that of non-division driving one by 14% in experiments and 11% in simulations. These findings suggest that multi-division excitation enhances acoustic scattering of microbubbles and may improve CEUS performance in deep tissues and fine vasculature.

It is well known that a collective collapse of cloud cavitation induces a shock wave emission, whose destructive power has been utilized in both medical and environmental fields. Therefore, it is important to elucidate the mechanism of how the shock wave is generated in association with the cloud collapse. In our previous study, we reported that the main shock wave is emitted by the collapse of the high-void fraction region in the cloud (referred to as the “nucleus of the cloud”) from macroscopic perspective; however, the detailed mechanism on how the main shock wave is formed has not been sufficiently understood, and further experimental investigations are required to clarify it. In this study, we made an experimental observation of the cloud-induced shock wave by using ultra-high-speed photography. In our experiment, the cloud was created by submerged pulsed water-jet injection, and its unsteady motion and the shock wave phenomena were recorded by a high-speed camera operating at 1,700,000 fps. Finally, our observations revealed multiple shock wave emissions during the cloud collapse as well as weak pressure waves prior to it. These findings suggest that the main shock wave from the cloud collapse originates from the accumulation of these weak pressure waves.

To mitigate wheel-separation accidents involving heavy-duty vehicles, a new impact-hammer technique has been developed that enables rapid, quantitative diagnosis during daily pre-trip inspections. Conventional inspection hammers detect only a 0 % wheel-nut torque ratio, offering no gradation of fastening integrity. In the proposed method, the tip of a stainless-steel rod is struck with an accelerometer-equipped hammer, and the resulting response waveform is analysed; the peak time lag (delay time) between its deformation and recovery phases is used as the diagnostic index. Analysis of this delay time showed that the technique can be applied to evaluating the fastening integrity of wheel nuts.

In this study, ultrasonic vibration was applied to the mold during the hand lay-up molding process to promote resin impregnation into reinforcing fibers and to reduce residual voids. Special mold capable of applying high-intensity vibration was developed, and the effect of ultrasonic vibration on mechanical properties of the molded plate is investigated. Video camera monitoring shows that the time required for resin impregnation decreased under vibration-assisted molding. In acoustic emission (AE) measurements, the specimens molded with ultrasonic vibration showed a delayed onset of initial damage in the case of cross-ply fabric. Cross-sectional observations also confirmed that ultrasonic vibration could reduce unimpregnated regions and residual voids in the molded plates with cross-ply fabric.

In VaRTM (Vacuum assisted Resin Transfer Molding), the resin impregnation of fiber bundles significantly influences the quality of molded products. Efforts have been made to enhance the impregnation state of fiber bundles by mechanical vibration. In our previous research, high-intensity ultrasonic vibration is applied to the VaRTM mold, and its effect on resin flow and impregnation is confirmed. In this study, the mechanical properties changes of VaRTM molded plates due to ultrasonic vibration is investigated. Although there are no significant differences in visual observation of the molded plates, microscopic observation revealed the decrease of unimpregnated fibers in the plate with ultrasonic vibration. It was also found that tensile strength could be improved by application of ultrasonic vibration during the resin filling process.

In this study, the improvement of the measurement accuracy of the discharge field temperature by using the high-speed camera is investigated. In the method, the temperature measurement accuracy depends on the accuracy of the shock wave local velocity. The local velocity accuracy can be determined by the spatial resolution of the high-speed camera. Therefore, in order to improve the accuracy, the high performance camera is one of the promising method. As a result, by using the three times finer spatial resolution camera, the temperature accuracy became three times higher compared to the previous results. This result suggests that the method is expected to extend to the future development of the simultaneous measurement of the vorticity and the temperature.

Solid–liquid two-phase flow is a one of multiphase flow phenomenon used in the energy and chemical fields. Understanding blockages caused by solid-phase deposition and insufficient liquid-phase flow in pipelines is essential for ensuring operational safety and risk management. This study focuses on developing measurement technology using ultrasound to monitor solid–liquid two-phase flow. This paper presents a method for the real-time measurement of the size of flowing coarse particles, with the aim of achieving solid-phase flowrate measurement in solid–liquid two-phase flows using pulsed ultrasound. The accuracy of the developed measurement method was verified, demonstrating the ability to measure solid phase size with a relative error of 5% in water-resin sphere two-phase flow. Furthermore, it was also demonstrated that the influence on measurement accuracy was minimal, even when micro silica sand particles were introduced as a source of noise.

Non-invasive blood flow measurement methods such as ultrasound Doppler and laser Doppler face challenges, including difficulty in measuring low flow velocities and limitations to the skin surface. To address these issues, we focus on the photoacoustic effect, which has the potential to overcome the limitations of both methods, aiming to measure blood flow velocity in small vessels at moderate depths. In this study, we applied the pulsed wave Doppler method to estimate displacement and compared the results with those obtained using the time-delay method. In the experiment, particles were introduced into a flow pass and moved, and the estimated flow velocity was calculated from the phase difference of the signals. The experimental results showed that the time-delay method closely matched the theoretical values, whereas the pulsed wave Doppler method tended to underestimate the flow velocity. This underestimation is considered to be caused by an overestimation of the photoacoustic frequency in the pulsed wave Doppler method, suggesting that improvements in frequency determination are necessary．

It is well-known that the thickness of the arterial wall increases in response to hypertension. This is considered to be a homeostatic response of vascular smooth muscle cells to maintain circumferential stress within the wall at a constant level in a physiological condition. However, such homeostatic response does not appear in the axial direction. In fact, axial stress is not maintained at a constant level and instead decreases in response to hypertension. To investigate the cause of this, we examined the deformation of smooth muscle cell nuclei within the vessel wall during tensile loading. As a result, nuclear deformation in response to circumferential stretch was about 25% of the tissue deformation, whereas it was only about 5% in response to axial stretch. Nuclear deformation has been suggested to enhance protein synthesis. Therefore, the small degree of nuclear deformation in the axial direction may be a reason why axial stress is not maintained in response to hypertension.

Heart failure is a growing global health crisis, exacerbated by aging populations worldwide, including in Japan. Despite advances in medical treatment, the prevalence of heart failure continues to rise, posing severe challenges to healthcare systems and economic and social infrastructures. Heart failure leads to a vicious cycle of increased cardiac energy consumption and functional decline, underscoring the importance of cardiac energy metabolism abnormalities in disease progression. However, real-time monitoring of myocardial energy metabolism, particularly ATP dynamics, has been technically difficult. We developed a novel mouse model (AVID mouse) expressing FRET-based ATP sensor enabling in vivo visualization of rapid ATP fluctuations. Using isolated cardiomyocytes from both wild-type and heart failure AVID mice, we established a method to measure myocardial energy efficiency in real time by calculating the ratio of ATP consumption to contraction. Administration of the selective cardiac myosin activator Omecamtiv Mecarbil (2 nM, 1 hour) significantly improved energy efficiency by approximately 15%. Longitudinal analysis demonstrated that energy efficiency in heart failure mice decreased with increasing heart weight-to-body weight ratio, reflecting cardiac hypertrophy and dysfunction. This methodology enables screens for pharmacological agents that improve myocardial energy efficiency, offering potential for novel therapeutic strategies to inhibit heart failure progression.

Cancer cells form thin fibers that connect them to each other, called tunneling nanotubes (TNTs), which enable intercellular communication. TNTs are understood to serve as pathways for the transmission of various cellular materials and signals and are thought to play roles in cellular physiological activity and the survival of cancer cells. We investigated the mechanical properties of TNTs by varying the elastic modulus of cell adhesion substrates (E = ~GPa, ~MPa, ~100kPa), based on the hypothesis that TNTs may contribute to the transmission of mechanical stress between cells. First, we observed cell adhesion to substrate with different elastic modulus using human cervical cancer (HeLa) cells under fluorescence microscopy. Then, the internal tension, axial spring constant, and elastic modulus of TNTs were estimated from force-displacement curves obtained by indentation measurements using an atomic force microscope. As a result, it was shown that the cell adhesion area and TNT internal tension increased on the hard substrate with elastic modulus in the GPa range, and no significant difference were observed in TNT axial spring constants and TNT elastic modulus. However, no differences were observed in cell adhesion area or TNT mechanical properties between the substrate with the ~100 kPa and MPa orders. HeLa cells might not be able to detect these slight differences in the elasticity of the substrate. Overall, our results indicate that TNTs may influence neighboring cells by transmitting mechanical cues in a manner dependent on the extracellular mechanical environment.

With the increasing use of collaborative robots, minor injuries caused by contact with machines have become a growing concern. This study aims to simulate minor finger injuries using a rabbit hind limb model as a human tissue surrogate. CT data were processed into a 3D hexahedral mesh model including skin, muscle, and bone. Finite element analysis was performed using a cylindrical impactor (10 mm diameter) under conditions matching in vivo experiments (20 mm/s, 130 N). The simulation reproduced localized stress concentration and skin rupture similar to experimental observations, showing skin tearing and muscle exposure. The constructed model enables analysis of transient loading conditions, simulating scenarios where the rabbit hind limb substitutes for the human finger. The constructed model enables detailed analysis of transient loading conditions, providing insights into the mechanisms underlying minor injuries caused by robot collisions.

Coronary artery disease is a condition in which fatty substances and plaque accumulate in the coronary arteries, leading to atherosclerosis and narrowing of the arteries. One treatment method involves inserting a metal mesh tube called stent into the blood vessel to expand and secure at the disease, thereby ensuring blood flow. The materials of coronary artery stent are Co-Cr alloys and stainless steel, and these materials remain in the body semi-permanently even after recovery and also in some cases, removal surgery may be necessary if they may cause restenosis. As an alternative material, magnesium (Mg), one of the essential elements for the human body, is being considered because it has low toxicity even when corroded in the body. However, the corrosion behavior of Mg in the body is unclear, and there are challenges in controlling the duration of strength retention. In this study, corrosion tests on magnesium were conducted under flow conditions simulating coronary arteries by using simulated body fluid developed by Kokubo et al. , physiological saline solution, and distilled water. The corrosion behavior of magnesium was evaluated through surface observation, corrosion potential measurement, and elemental analysis of corrosion products.

Alumina-toughened zirconia composites (ATZ) have attracted much attention in biomaterials such as artificial hip joints and implants. ATZ has excellent mechanical properties and is resistant to degradation at low temperatures. However, ATZ is bioinert, meaning that it does not bond with bone, which is a problem after implantation. In this study, we are searching for a surface that promotes cell proliferation and differentiation on ATZ. We are fabricating specimens with various surface roughness and shapes, and investigating their osteogenic properties and strength.

Polylactic acid (PLA) is a biodegradable polymer material used as a material for medical devices, because PLA breaks down in the body and doesn’t need to be removed. Injection molding methods have been used for the processing of PLA. On the other hand, processing methods using fused filament fabrication (FFF) 3D printers have attracted attention in recent years. Using FFF 3D printers, it is possible to create medical devices that are optimally tailored for each patient. When we apply PLA in medical devices, data on mechanical properties related to degradability are essential. In previous studies, test pieces were made micro-size to enable efficient testing, making it impossible to attach extensometers and calculate accurate strain. In this study, we used digital image correlation (DIC) to calculate the accurate strain of PLA test piece and evaluated their mechanical properties related to degradability. PLA test pieces were fabricated using an FFF 3D printer and immersed in saline before tensile tests. As a result, the maximum tensile stress and breaking energy decreased after 90 days of immersion. On the other hand, no significant change was observed in the tensile elastic modulus after 210 days of immersion. When comparing the strain calculated from the displacement of the testing machine's crosshead and the strain calculated by DIC, there was a large difference between them. It became clear that this difference had a significant impact on the evaluation of mechanical properties of PLA. The tensile elastic modulus calculated by DIC was close to previously known values, demonstrating that accurate strain measurements using DIC are available for evaluating the mechanical properties of micro-size PLA test pieces.

The mechanical interaction between cancer spheroids and the extracellular matrix (ECM) plays a critical role in tumor invasion. In this study, we investigated the invasive behavior of cancer spheroids embedded in a three-dimensional collagen ECM of fixed concentration. By applying digital volume correlation (DVC) analysis to time-lapse volumetric images, we visualized the spatial distribution and temporal evolution of strain fields around the invading spheroids. In addition, fiber orientation analysis was employed to evaluate ECM structural changes in response to invasion. The results demonstrated that active protrusive regions exhibited localized high strain and reoriented collagen fibers. These findings suggest that mechanical strain and ECM fiber orientation can serve as sensitive indicators of tumor invasion dynamics in 3D culture systems.

Honeycomb core sandwich panels (hereinafter, HSP for brevity) exhibit excellent energy absorption under overall compressive loads. However, they are prone to local deformation under localized compressive loads, which may lead to structural failure. In this study, woven CFRP was used for the face sheets, and stiffness distribution was introduced by varying the number of laminate plies in different regions to enhance impact mitigation. Drop weight impact tests were conducted to obtain load-displacement curves, and the energy absorption capacity was evaluated based on the deformation up to either the peak load or the onset of local damage. As a result, it was confirmed that placing a circular high-stiffness region directly under the impact point improved energy absorption performance compared to a uniformly stiff panel. On the other hand, when a ring-shaped high-stiffness region was used, stress concentration occurred at the stiffness boundaries, which reduced the impact mitigation performance. These findings indicate that appropriate stiffness distribution in CFRP face sheets can significantly influence the energy absorption characteristics of HSP.

When mechanical structures such as aircraft are used over long periods, random loading can cause crack initiation, potentially leading to fatigue failure. Accurate prediction of fatigue life under random loading is therefore essential for structural design and maintenance scheduling. In this study, we attempted to improve the accuracy of fatigue life prediction while maintaining simplicity by calculating crack propagation life from crack growth rate curves and incorporating crack propagation mechanisms into an equation based on the linear damage accumulation rule. This method utilizes crack opening stress, which is influenced by the loading history of past stress amplitudes, making its accurate estimation crucial for fatigue life prediction. Accordingly, we investigated the effect of compressive stress—applied during aircraft takeoff and landing—on crack opening stress using aluminum alloy A2024-T4, commonly used in aircraft. Crack opening stress was examined through constant amplitude tests and two-step variable amplitude tests. In the constant amplitude tests, it was confirmed that the opening stress decreased when the stress ratio exceeded a certain value. In the two-step variable amplitude tests, when the insertion ratio of compressive stress was 1/11, the behavior was similar to that under constant amplitude with compressive stress; when the insertion ratio was 1/101, the behavior resembled that without compressive stress.

In this study, we established a fabrication method for three-dimensional hybrid construct by combining the cell sheet technology and the electrospinning method for polymer scaffolds. Two sheets of mouse skeletal myoblasts cells (C2C12) were prepared and laminated onto a polymeric tubular scaffold to construct a 3D hybrid structure. Mechanical tensile tests revealed that the hybrid construct exhibited enhanced Young’s modulus, tensile strength, and fracture energy compared to the pure tubular scaffold. By comparing the stress-strain curves, it was demonstrated that the deformability of tubular structure dramatically increased due to the introduction of cell sheets. These findings suggested that such biological composite structure offers improved mechanical properties suitable for cardiac tissue engineering applications. This work provides a foundational approach toward developing functional cardiac tissues for regenerative medicine.